During one type of common orthodontic treatment, a series of small brackets are fixed to a patient's anterior, cuspid and bicuspid teeth, and an archwire is inserted into a slot of each bracket. The archwire forms a track to guide movement of the teeth to orthodontically correct locations. End sections of the archwires are typically captured in tiny appliances known as buccal tubes that are fixed to the patient's molar teeth. Many types of orthodontic brackets have archwire slots that are open on one side for insertion of the archwire, and confined on remaining sides by the bracket tie wings or other structure. Brackets bonded to the patient's front tooth surfaces often have archwire slots that open on a buccolabial side (facing the patient's cheeks or lips) or an occlusal side (facing the outer tips of the teeth) of the archwire slot.
Ligatures such as elastomeric O-rings are commonly used to connect the archwire to each bracket and to urge the archwire into seating engagement in the archwire slot. However, ligatures are time-consuming to install, decay over time and can become stained and unsightly. As a result self-ligating brackets were developed wherein each bracket has a clip or latch mounted thereon for retaining an archwire in the archwire slot. Christoff et al. U.S. Pat. No. 6,071,119, describes one such self-ligating bracket and contains an extended discussion of different types of known self-ligating bracket system in its background section. Voudouris U.S. Pat. Nos. 5,908,293 and 5,913,680, among others, illustrate that a wide variety of self-ligating bracket structures have been proposed.
Most known self-ligating bracket systems do not require complete removal of the clip when it is necessary to access the archwire slot. The clip or shutter can assume open and closed positions without being fully removed from the bracket. Known U-shaped clips slide into and out of these positions and use some form of detent to hold the clip in the open position. In the open position, the archwire slot is accessible, but the clip has not been fully removed from the bracket.
Build-up of calculus over time can make it difficult to remove shutters or clips that slide into and out of place, such as of the detent style. Hinged designs avoid this problem, but it is also desirable to avoid elaborate structures such as built-in hinges where possible, while still providing a clip that performs reliably, is easy to use and inexpensive to manufacture. The present invention addresses these needs.